Ledger & payment correctness
Double-entry ledgers, invariants, reconciliation as a first-class system, idempotency and exactly-once orchestration. The unglamorous machinery that decides whether the numbers are right.
Financial infrastructure consulting
Payment systems that don't lose money.
I'm Breno Coelho — 21+ years of software engineering, building financial systems since 2005 and working exclusively in payments and fintech for the last four. I keep ledgers balanced, settlements reconciled, and lately, AI-written code from breaking the money.
21+ years in software engineeringFinancial systems since 2005Payments & fintech full-time since 2022Go · Rust · Temporal · PostgresQuint specs & property-based testingFiat ↔ on-chain in production
What I work on
One specialty — correctness where money is involved — applied at three layers.
AI that doesn't break the money
Correctness under autonomy: formal specs, property tests and types as gates — so AI-written financial code and autonomous payment agents respect invariants that must never be violated.
Fiat ↔ on-chain settlement
Hybrid settlement under regulation: reconciling on-chain finality with off-chain ledgers, reorgs, custody and auditability in the GENIUS-era stablecoin landscape.
Track record
Attested work, not aspiration — the systems behind the writing.
One payment architecture, six rails
At 3thix — the web3 payments arm of a major game-distribution ecosystem — I architected the unified payment layer integrating Stripe, Adyen, NMI and Nuvei with EVM chains and Solana: fiat and on-chain settlement behind one set of invariants.
Auditability regulators can query
As founding engineer at a US payments startup, I designed the audit-logging architecture — structured events across Go microservices — that gave compliance a complete, queryable history of every transaction, across jurisdictions.
Fluent on the bank side too
From PeopleSoft financial modules (AP/AR/Treasury) in 2005 to leading cards & payments projects with Visa and payment processors at a state bank — I speak the language of banks and regulators, not just startups.
Work with me
I work with fintech teams on the things that decide whether the numbers are right — ledgers, settlement and payment-system correctness, and adopting AI in a codebase that moves money. Open to senior and staff engineering roles as well as consulting engagements. If that sounds like your problem, I'd like to hear about it.
Email me